With the explosive growth of the Internet, multitudes of users are connecting to the Internet through their phone lines. While many businesses allow for dedicated phone lines to their computers and different dedicated lines for voice communications, many smaller businesses and home users cannot afford the expense of a dedicated phone line. If a user chooses to use their voice phone line for their Internet communications, while the person is logged on to the Internet (or any other form of data communications) the phone will ring busy if anyone tries to call the phone number being used for the outgoing connection. This can be problematic since access to online services and online providers often results in intervals of long duration in which the user is logged on to the communication provider. This means long intervals where the phone line will ring busy if someone is trying to reach the user over a conventional telephone. In addition, using the existing technologies, someone desiring to place a call while logged on to a data network would cause the data portion of the line to time-out due to inactivity while the user toggled to the other session using 3-way calling or similar technology.
In theory, this is solved by `call waiting` in that a user who is talking on the phone will hear a tone if someone else is trying to reach them. This is not the case where the initial usage is with a data service provider which sends and receives all messages as tones. Since the data service will receive the `call waiting` tone as part of the message, most applications will terminate with fatal or unrecoverable errors if a `call waiting` interrupt comes in while a data communication session is established causing the workstation to hang-up on the call with the data service provider. While this may allow the user to receive incoming calls, it is not desirable to force the user off the data communications session to be notified of the incoming call. The user should have a choice as to whether they are going to receive the incoming call without disconnecting them from the data communications network to which they are connected.